Web Services

Web Server

• A web server is a computer system that processes requests via HTTP to distribute information on the Web

• The term can refer to the entire system or the software

• A static web server serves hosted files to the client

• A dynamic web server consists of a static web server with extra software (commonly an application server and a database) that generates content for each client request

Web Services

• A web service is a service offered by an electronic device to another electronic device where the devices communicate over the Web.

• Web services are intended for machine-to-machine communication and exchange data in machine readable formats such as XML or JSON.

• There are two major categories of web services:

  • REST-compliant web services: manipulate representations of web resources using a uniform set of stateless operations.

  • Arbitrary web services: expose an arbitrary set of operations.

Web Service Categories

• A traditional web service describes a standardized way of integrating web-based applications using the XML, SOAP, WSDL, and UDDI open standards.

  • XML: the data exchange format

  • SOAP: transfers the data

  • WSDL: describes the services available

  • UDDI: lists the available services

• More modern REST-compliant web services expose resources as URLs and perform stateless operations on the resources using HTTP verbs.

Web 2.0

• Web 2.0 refers to websites that emphasize:

  • user-generated content

  • usability

  • interoperability

• Examples of Web 2.0

  • Social networking sites

  • Blogs

  • Wikis

  • Video sharing sites

  • Mashups

• Web 2.0 applications often utilize web services for their functionality

Web API

• A web API is an application programming interface (API) for either a web server or a web browser.

• A server-side web API is a programmatic interface exposing endpoints via the web to a defined request-response message system.

• A client-side API is a programmatic interface to extend the functionality within a web browser.

Web Resource vs. Web Service

• Many Web 2.0 applications have moved away from SOAP-based web services towards collections of RESTful web resources.

• RESTful web APIs are accessible via standard HTTP methods.

• RESTful web APIs tend to be less resource intensive when JSON is used as the data exchange format.